The long-term goal of this proposal is to develop an effective treatment for developmental prosopagnosia and to understand the mechanisms of treatment-related improvements. This is relevant to the National Eye Institute's mission to better treat visual disorders and understand mechanisms of visual function. The particular goal of this proposal is to build on our previous successes at improving face processing in developmental prosopagnosics (DPs) using cognitive training targeting holistic face processing. Our specific aims for this proposal are to: 1) Determine whether an improved, longer version of the holistic face training program is more effective at improving face processing and daily functioning in developmental prosopagnosics (DPs) than active control training; 2) To use functional MRI to characterize how core and extended face processing regions change after holistic face training compared to active control training; and 3) To characterize how event-related potential (ERP) signatures of face processing change after holistic face training compared to active control training. As an exploratory aim, we also seek to determine if face-selective white matter tracts in ventral occipito-temporal regions change after holistic face training compared to active control training. To achieve these aims, we propose to run a triple-blind (assessor, participant, and data analysis is blind to treatment), randomized longitudinal treatment study with 50 DPs. We propose to have 25 DPs complete 6 weeks of holistic face training and 25 complete 6 weeks of a matched active control training that uses the same faces. After screening, DPs will perform baseline cognitive and functional assessments as well as MRI scans (including fMRI and DTI) and ERP recording. Next, DPs will be randomized to either holistic face training or active control training and will train on a laptop computer at home or in the laboratory for 30 sessions (36 mins/session) over 6 weeks. During this time, a cognitive training coach will closely monitor their progress. Within one week of intervention completion, DPs will repeat the behavioral assessments, MRI scans, and ERP recording. To measure the longevity of training effects, DPs will also repeat all assessments after a 6-week no-contact period.